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dished $121125 JOHN S. D UNHAM AND JAMES GREEN, STQLOUIS, MISSOURI.

Letters Patent No.195,671, dated October 12, 1869.

To all whom it may concern:

, Be it known that we, J our S. DUNHAM and JAMES GREEN, of the city of St. Louis, in the county of St.

Louis, and State of Missouri, have made certain new and useful Improvements in Baking-Ovens; and we do hereby declarethe following to beafull and true description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon.

This invention relates to such a construction of the oven that the baking may be continued therein'without interruption during the time of recharging the fires; the arrangement of heat-passages and; flues being such that the hot gases arising from the combu'stion may be passed into the baking-chamber when clear of smoke, or may be excluded therefrom when not clear; said chamber being always ,heated from the fines and passages about and surrouj'ndingthe same,

as well as by the introduction of. heated air or gases into the same when deemed proper;

This invention further relates to the arrangement of air-ducts to supply airnot unduly-parched or dried by combustion,-within the baking-chamber, as may be necessary in baking. To enable those herein skilled to make and use our said invention, we will now more fully describe thesame, referring herein to the accompanying Figure 1 as a front view; to

Figure 2 as a transverse section at .line a: y of the plan, as.shown in g r Figure 3, which is a sectional view'at line 1: y of fig. 2; and to Figure 4 as a section at line :0 y of-plau, fig. 2.

We form enclosing-walls A, forour said oven, of proper material, usually fire-brick, and generally in the arrangement shown in the several figures,"

At the fi'ont, we'locate the fire-places B, the grates being usually set back from the face of the oven.

The fire-places are arranged with proper doors and ash-pits, in the usual manner. g

From the fire-places Bthe hot air passes back in the passage 0 to the rear end of the oven, to rise by 'the tines D.

The floor E' is immediately over the passage 0, resting, by suitable (fire-clay) blocks o upon the base wall A, and above the floor E is the second floor F, forming the bottom or floor of the baking-chamber, and resting by blocks f on the floor E.

The floors,E and F are usually made of fire-clay, flanged tiles, or similar plates, and between them form the passage E, in which the heated air or gases pass forward, thus acting to heat the oven-chamber which is directly above, and distribute over the entire width of the oven-base.

At the front wall of the oven are the rising 'flues G, which carry the heat up to the passage H. This is formed between the top or crown of the ovenI and the second top or cover K, and extends to the rear end of the oven, connecting them with the chimney L. y 1

The hot gases thus have been-passed forward under the entire base .of the oven, by the passage E, up the front, and then back over the entire crown, by the passage H. v

. The fines D connect, by their oontinuatious D, with the chimney L. Thus, if desired, a body of hot air may be made to enca'se the back of the 0ven,and complete the heating-surface Whichthus envelops the chamber M on all four sides.

Connecting with the passage E, we arrange on the other sides of the oven the flues N, which lead to the interior of the oven-chamber M. These flues have dampers n,.operated by a lever from without, to regulate or check the incoming flow 'of' heated gases. If the dampers-n are closed, then these fines are reservoirs of hot air, completing with the flues and passages above described, the hot-air encasement of the;

oven-chamber. The oven-chamber has doors m, aud above, these are the fines M, leading to the passage H, dampers m regulate the passage of heated air in said flues.

. In case of undue heat inthe oven, the fines M will act to relieve the same.

The entrance from the flues D to the passage E is controlled by a damper, d, and the entrance to: the

flue D is controlled by a damper, d. If the fiue-passage to E is closed, the damper d being opened, the

hot air goes directlyto the chimney, avoiding the oven proper. Similarly there are dampers g in the rising flues G.

By all said dampers the temperature at difi'erent parts of the oven may be regulated as required; and when the baking-chamber'has attained its heat, by v judicious regulation of said dampers, a casing of hot air maybe maintained about said chamber to preper've the oven-heat at an economical expenditure of uel.

If fresh fuel is added, causing smoke, the operator closes the dampers 1:, to out off the entrance of the gases to the inner oven, the baking being continued as ordinarily.

To produce a thorough baking, it is frequently necessary to avoid undue desiccation-of the rarefied oven-atmosphere, by introducing moisture. For the achievement of the same efiect, we introduce air tothe oven-chamber as follows: Between the fire-places we arrange air-ducts 0, controlled by proper slides or valves, in passing air over the top of the fireeplace, and then back to the flues D and passage raga-emerthe oven by the side flues N.

This introduction of air also reduces any nndue'- heat in the passage E. Similarly at the rear of the even there are air-passages O.

The combustion of the fuel will be aided by airdncts 11, arranged as indicated in fig. 4.

. A damper, l, regulates the passage of hot air to the chimney or confines the heat to the crown of the oven.

Having thus fully described our said invention,

What we claini, is

1. The arrangement of the passages G and D, extending under the'fnllwidth of the oven-floors, with fines G or D, and the passage H, extending over the full width of the oven crown, for distributing and equalizing the heat about the even, snbstantiall as set forth.

2. The side flues N, with dampers n, to carry heated air into the bakingchamber, in combination with the fines M and dampers m, tobarry ofi' the heated air,

when necessary, substantially as set forth. I

3. The air-ducts 0, controlled by proper slides, combined with the passage 0, fines D, and passage E, and side flues N,

. J OHN S'. DUNHAM. Witnesses: JAMES GREEN.

GEO..P. HEETHEL,

WILLIAM W. HERTHEL.

V to carry'air into the baking-w chamber, substantially as set forth. 

